The author is saying two things. One, that there has to be light for a shadow to form. Mainly because a shadow is you blocking the sun from hitting the ground. Two, if there's no light,a shadow won't
form because there is no light to hit the ground at all in that certain place so, a shadow will not form. The author is probably talking about a show forming!
form because there is no light to hit the ground at all in that certain place so, a shadow will not form. The author is probably talking about a show forming!